1. Field of the Invention
The invention relates to a telescopically adjustable support, particularly for a camera tripod, comprising at least two telescopically engageable tubes of which the outer tube has circumferentially disposed apertures at the push-on end engaging over the inner tube, axially divided elastic locking means which are provided on the push-on end of the outer tube, extend over the zone of engagement of the inner and outer tubes to surround same and have projections engaging through the apertures of the outer tube as well as clamping means engaging the inner tube beyond the outer tube, and fixing means co-operating with the locking means and acting on the clamping means thereof.
2. Description of the Invention
A telescopically adjustable support of the kind referred to is known for example from DE-OS No. 2 617 313. In the known support, the locking means comprise two separate parts, namely an externally screwthreaded sleeve to be placed over the push-on end of the outer tube and a locking sleeve or clamping ring, both parts containing an axially throughgoing slit to facilitate placement over the tubes. The clamping ring is provided with annular oblique faces at both ends, one of these engaging between the outer and inner tubes and the other co-operating with a complementary oblique face on the inner periphery of a nut which can be screwed onto the sleeve and constitutes the fixing means.
In this arrangement, for which the tubes, the sleeve, the clamping ring and the nut must of course all be round, use is made of an axial clamping motion in order to fix the inner tube to the outer tube at whatever distance it has been inserted therein, the inner tube being guided and clamped tight by the relatively close oblique faces at the two ends of the clamping ring.
The projections which are provided on the sleeve and engage through apertures in the outer tube are radially shorter than the spacing between the external faces of the outer and inner tubes and they merely serve as an abutment for an annular shoulder provided on the push-in end of the inner tube, whereby to prevent complete withdrawal of the inner tube from the outer tube when the fixing nut is untightened.
In the known telescopically adjustable support, it is a disadvantage that the locking means consist of two separate parts which call for two different manufacturing apparatuses, complicate assembly and therefore give rise to higher production costs than for locking means made in one piece. Further, since the clamping ring should not exceed a certain length, the retention of the inner tube brought about by it is not as secure as may often be desired. A camera tripod utilizing such supports is insufficiently stable. Finally, it should be repeated that only round profiles are feasible because of the axial clamping motion.